from dotenv import load_dotenv
import logging
import requests
from typing import Optional, Dict, Any
import os
from fastapi import FastAPI, HTTPException, Request
import json
import urllib3


# ============================================================================
# CONFIGURACIÓN
# ============================================================================

# Cargar variables de entorno desde .env
load_dotenv(dotenv_path=".env")

SAPB1_SL_URL = os.getenv("SAPB1_SL_URL", "")
SAPB1_SL_USER = os.getenv("SAPB1_SL_USER", "")
SAPB1_SL_PASSWORD = os.getenv("SAPB1_SL_PASSWORD", "")
SAPB1_SL_COMPANYDB = os.getenv("SAPB1_SL_COMPANYDB", "")
# Tiempo de espera y verificación SSL
SAPB1_SL_TIMEOUT = float(os.getenv("SAPB1_SL_TIMEOUT", 15.0))
SAPB1_SL_VERIFY_SSL = os.getenv("SAPB1_SL_VERIFY_SSL", "False").lower() == "true"

# ============================================================================
# Obtiene el logger específico de este archivo
logger = logging.getLogger(__name__)

# ============================================================================
# 1. Diccionario global para persistir las cabeceras de autenticación de SAP
sap_session_store: dict[str, Optional[dict[str, str]]] = {
    "headers": None
}

# ============================================================================
def _log_response(
    method: str,
    endpoint: str,
    response: requests.Response,
    request_data: Optional[Dict] = None
) -> None:
    """Registra detalles de la respuesta"""
    extra = {"http_method": method, "endpoint": endpoint, "status_code": response.status_code}
    if response.status_code >= 400:
        try:
            error_detail = response.json()
            respuesta = json.dumps(error_detail, indent=2)[:500]
        except Exception:
            respuesta = response.text[:500]
        logger.error(
            f"[{response.status_code}] {method} {endpoint} - "
            f"Datos enviados: {json.dumps(request_data, indent=2, default=str)[:500]} - "
            f"Respuesta: {respuesta}",
            extra=extra
        )
    else:
        logger.info(f"[{response.status_code}] {method} {endpoint}", extra=extra)

# ============================================================================
def ensure_sap_session(force_refresh: bool = False) -> dict:
    """
    Verifica si existe una sesión global de SAP B1 (B1SESSION).
    Si no existe o si force_refresh es True, realiza el Login con la información del .env.
    """
    if sap_session_store["headers"] and not force_refresh:
        return sap_session_store["headers"]

    logger.info("Iniciando sesión global en SAP como Manager...")
    auth_url = f"{SAPB1_SL_URL}/Login"
    sap_auth_payload = {
        "CompanyDB": SAPB1_SL_COMPANYDB,
        "UserName": SAPB1_SL_USER, 
        "Password": SAPB1_SL_PASSWORD
    }
    
    try:
        response = requests.post(
            auth_url, 
            json=sap_auth_payload, 
            timeout=SAPB1_SL_TIMEOUT,
            verify=SAPB1_SL_VERIFY_SSL
        )
        
        if response.status_code != 200:
            logger.error(f"Error crítico: No se pudo conectar el usuario Manager a SAP. Status: {response.status_code}")
            sap_session_store["headers"] = None
            raise HTTPException(status_code=response.status_code, detail="Conexión fallida con el servidor SAP")

        sap_session = response.json()
        b1_session_id = sap_session.get("SessionId")
        route_id = response.cookies.get("ROUTEID")

        headers = {
            "Cookie": f"B1SESSION={b1_session_id}; ROUTEID={route_id}"
        }
        sap_session_store["headers"] = headers
        logger.info(f"Sesión global establecida. B1SESSION: {b1_session_id[:10]}...")
        return headers
    except requests.RequestException as exc:
        logger.error(f"Error de conexión al autenticar contra SAP: {exc}")
        sap_session_store["headers"] = None
        raise HTTPException(status_code=500, detail=f"Error al conectar con SAP Service Layer: {exc}")

# ============================================================================
# FUNCIÓN PROXY CENTRALIZADA
# ============================================================================
def forward_to_sapb1(
    method: str,
    endpoint_path: str,
    json_data: Optional[Dict[str, Any]] = None,
    params: Optional[Dict[str, Any]] = None,
    extra_headers: Optional[Dict[str, str]] = None
) -> requests.Response:
    """
    Función proxy centralizada para todas las llamadas a SAP B1 Service Layer.
    Maneja autenticación transparentemente con sesión única y reintento.
    """
    if not method or not endpoint_path:
        raise ValueError("method y endpoint_path son requeridos")
    
    method = method.upper()
    
    # Obtener cabeceras con B1SESSION
    headers = ensure_sap_session()
    
    # Preparar URL
    url_destino = f"{SAPB1_SL_URL}/{endpoint_path}"
    
    # Preparar cabeceras de la petición
    req_headers = {
        'Content-Type': 'application/json',
        'Accept': 'application/json'
    }
    req_headers.update(headers)
    if extra_headers:
        req_headers.update(extra_headers)
    
    log_extra = {"http_method": method, "endpoint": endpoint_path}
    logger.info(f"[{method}] {endpoint_path}", extra=log_extra)

    # Realizar solicitud
    try:
        response = requests.request(
            method=method,
            url=url_destino,
            json=json_data,
            params=params,
            headers=req_headers,
            timeout=SAPB1_SL_TIMEOUT,
            verify=SAPB1_SL_VERIFY_SSL
        )
    except requests.exceptions.Timeout:
        logger.error(f"Timeout ({SAPB1_SL_TIMEOUT}s) en {endpoint_path}", extra=log_extra)
        raise ConnectionError(f"Timeout al conectar con {endpoint_path}")
    except requests.exceptions.ConnectionError as exc:
        logger.error(f"Error de conexión: {exc}", extra=log_extra)
        raise ConnectionError(f"No se pudo conectar con SAP B1: {exc}")
    except requests.RequestException as exc:
        logger.error(f"Error en solicitud: {exc}", extra=log_extra)
        raise ConnectionError(f"Error en solicitud HTTP: {exc}")

    # Manejo de 401 - Sesión expirada: reintentar UNA sola vez
    if response.status_code == 401:
        logger.warning("Sesión expirada (401). Reautenticando e intentando una sola vez...", extra=log_extra)
        try:
            # Forzar actualización de sesión
            headers = ensure_sap_session(force_refresh=True)
            req_headers.update(headers)

            logger.info("Reintentando solicitud [RETRY]", extra=log_extra)
            response = requests.request(
                method=method,
                url=url_destino,
                json=json_data,
                params=params,
                headers=req_headers,
                timeout=SAPB1_SL_TIMEOUT,
                verify=SAPB1_SL_VERIFY_SSL
            )
        except Exception as exc:
            logger.error(f"Error en reintento: {exc}", extra=log_extra)
            raise ConnectionError(f"Error en reintento tras reautenticación: {exc}")

    # Logging de respuesta
    _log_response(method, endpoint_path, response, json_data)

    # Extraer error SAP y propagar al frontend
    if response.status_code >= 400:
        error_msg = response.text
        try:
            err = response.json()
            error_msg = err.get("error", {}).get("message", {}).get("value", error_msg)
        except Exception:
            pass
        raise HTTPException(status_code=response.status_code, detail=error_msg)

    return response
# ============================================================================